Disclosed herein are colorant compounds. More specifically, disclosed herein are phthalocyanine colorant compounds particularly suitable for use in hot melt or phase change inks. One embodiment is directed to a compound of the formula
wherein M is an atom or group of atoms capable of bonding to the central cavity of a phthalocyanine molecule, wherein axial ligands optionally can be attached to M, each R′, independently of the others, is a substituent, each n, independently of the others, is 0, 1, 2, 3, or 4, each R″, independently of the others, is a substituent, each m, independently of the others, is 0, 1, 2, or 3, each R, independently of the others, is an alkylene group, an arylene group, an arylalkylene group, or an alkylarylene group, each X, independently of the others, is —OH, —COOH, or a group of the formula
wherein each Y and each Z, independently of the others, is a direct bond, an oxygen atom, or a group of the formula —NR1—, wherein R1 is a hydrogen atom, an alkyl group, an aryl group, an arylalkyl group, or an alkylaryl group, provided that Z and Y are not both direct bonds connected to a single C═O moiety at the same time, provided that when X is —COOH,
R can also be a direct bond, and each Rd, independently of the others, is an alkyl group, an aryl group, an arylalkyl group, or an alkylaryl group.
In general, phase change inks (sometimes referred to as “hot melt inks”) are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the recording substrate, either directly or via an intermediate heated transfer belt or drum, they quickly solidify to form a predetermined pattern of solidified ink drops. Phase change inks have also been used in other printing technologies, such as gravure printing, as disclosed in, for example, U.S. Pat. No. 5,496,879 and German Patent Publications DE 4205636AL and DE 4205713AL, the disclosures of each of which are totally incorporated herein by reference.
Phase change inks for color printing typically comprise a phase change ink carrier composition which is combined with a phase change ink compatible colorant. In a specific embodiment, a series of colored phase change inks can be formed by combining ink carrier compositions with compatible subtractive primary colorants. The subtractive primary colored phase change inks can comprise four component dyes, namely, cyan, magenta, yellow and black, although the inks are not limited to these four colors. These subtractive primary colored inks can be formed by using a single dye or a mixture of dyes. For example, magenta can be obtained by using a mixture of Solvent Red Dyes or a composite black can be obtained by mixing several dyes. U.S. Pat. Nos. 4,889,560, 4,889,761, and 5,372,852, the disclosures of each of which are totally incorporated herein by reference, teach that the subtractive primary colorants employed can comprise dyes from the classes of Color Index (C.I.) Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, and Basic Dyes. The colorants can also include pigments, as disclosed in, for example, U.S. Pat. No. 5,221,335, the disclosure of which is totally incorporated herein by reference. U.S. Pat. No. 5,621,022, the disclosure of which is totally incorporated herein by reference, discloses the use of a specific class of polymeric dyes in phase change ink compositions.
Phase change inks have also been used for applications such as postal marking and industrial marking and labelling.
Phase change inks are desirable for ink jet printers because they remain in a solid phase at room temperature during shipping, long term storage, and the like. In addition, the problems associated with nozzle clogging as a result of ink evaporation with liquid ink jet inks are largely eliminated, thereby improving the reliability of the ink jet printing. Further, in phase change ink jet printers wherein the ink droplets are applied directly onto the final recording substrate (for example, paper, transparency material, and the like), the droplets solidify immediately upon contact with the substrate, so that migration of ink along the printing medium is prevented and dot quality is improved.
Compositions suitable for use as phase change ink carrier compositions are known. Some representative examples of references disclosing such materials include U.S. Pat. Nos. 3,653,932, 4,390,369, 4,484,948, 4,684,956, 4,851,045, 4,889,560, 5,006,170, 5,151,120, 5,372,852, 5,496,879, European Patent Publication 0187352, European Patent Publication 0206286, German Patent Publication DE 4205636AL, German Patent Publication DE 4205713AL, and PCT Patent Application WO 94/04619, the disclosures of each of which are totally incorporated herein by reference. Suitable carrier materials can include paraffins, microcrystalline waxes, polyethylene waxes, ester waxes, fatty acids and other waxy materials, fatty amide containing materials, sulfonamide materials, resinous materials made from different natural sources (tall oil rosins and rosin esters, for example), and many synthetic resins, oligomers, polymers, and copolymers.
U.S. Pat. No. 6,472,523 (Banning et al.), U.S. Pat. No. 6,726,755 (Titterington et al.), and U.S. Pat. No. 6,476,219 (Duff et al.), the disclosures of each of which are incorporated herein by reference, disclose a compound of the formula
wherein M is an atom or group of atoms capable of bonding to the central cavity of a phthalocyanine molecule, wherein axial ligands optionally can be attached to M. U.S. Pat. No. 6,726,755 further discloses a phase change ink composition comprising a phase change ink carrier and this colorant compound. U.S. Pat. No. 6,476,219 further discloses methods for preparing these compounds.
While known compositions and processes are suitable for their intended purposes, a need remains for improved colorant compositions. In addition, a need remains for improved phthalocyanine compositions. Further, a need remains for colorants suitable for use in phase change inks. Additionally, a need remains for colorants that enable good to excellent lightfastness. There is also a need for improved colorants having improved cyan color for primary subtractive imaging. In addition, there is a need for improved colorants having high tinctorial power or spectral strength. Further, there is a need for improved cyan phase change ink colorants that are highly thermally stable in ink compositions for several weeks in air at temperatures exceeding 140° C. Additionally, there is a need for phase change ink colorants with low diffusion characteristic that will not bleed into inks containing other colorants. A need also remains for colorants with good to excellent lightfastness that are compatible with phase change ink vehicles. In addition, a need remains for colorants suitable for use in phase change inks that exhibit reduced or no variation in color over the life of the ink in the printer. Further, a need remains for colorants suitable for use in phase change inks that exhibit reduced or no variation in color subsequent to being deposited in imagewise fashion on substrates. Additionally, a need remains for colorants that have no carcinogenic or mutagenic effects. There is also a need for colorants that, when dissolved in phase change ink carriers, do not leave residues of material that might otherwise complicate filtration efficiency. In addition, there is a need for colorants that can be fine-tuned for compatibility with various phase change ink carriers. Further, there is a need for colorants that can be further derivatized to enable compatibility with phase change ink carriers.